Gene expression of immune and neuroendocrine-related genes and biometric data of small-spotted catshark embryos (Scyliorhinus canicula) after six days of exposure to deoxygenation and hypoxia.

The global oxygen inventory has been declining worldwide, primarily due to climate change. However, the effects of low oxygen levels on shark neuroendocrinology and immunology are not understood. This study investigated the neuroendocrine response and immune competence of the head and trunk tissues of early (EE; before pre-hatching) and late embryos (LE) of small-spotted catshark (Scyliorhinus canicula) under six days of deoxygenation (DO; 93% O2 of air saturation) and hypoxic conditions (26% O2). Catshark embryos were resilient to DO, showing only changes in gene expression for melanotransferrin and a 10% decline in survival. Under hypoxia, growth remained unaffected; however, survival decreased by 31% and exceptionally in LE, highlighting inadequate adaptive responses. The developmental stage affected the expression of immune response genes, pointing to critical response mechanisms. The EE stage showed a greater stress response under hypoxia compared to LE, with several changed immune genes, while hypoxia-inducible factor 1 alpha levels increased. The energy demands associated with coping with hypoxia compromised immune function, raising concerns about long-term species survival under climate change. These findings highlight the need for further research on sharks' resilience to environmental challenges and the interactions of metabolic pathways.
Here we show the gene expression (expressed as ΔΔCT) of immune and neuroendocrine-related genes in head and trunk samples of early (EE) and late embryos (LE), and biometric data of small-spotted catshark (Scyliorhinus canicula) after six days of exposure to deoxygenation (air saturation = 93%) and hypoxia (air saturation = 26%).